What is the solution of SMS under the existing network 4G LTE?

1. Different system measurements and cell reselection will be conducted.

2.2 calling and called process. CSFB is different. Sometimes, 4G networks send neighbor information to mobile phones. The data of these neighboring cells are manually matched, so there is no direct communication and authentication between E-UTRAN and UTRAN/GERAN. 2G only supports authentication version V 1, that is, one-way authentication of the network to the terminal.

3. Yes, the UE is connected to the MME through the 4G wireless network, and the MME is connected to the MSC, which sends and receives short messages without going through the 2/3G wireless network.

4. Yes. I don't think so. I haven't read the instructions. I don't know if there is standardization.

5. Gram weight

The above is about mobile and China Unicom, except that the target of CSFB is utran.